共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
Constraints on gold and copper ore grades in porphyry-style Cu–Au ± Mo deposits are re-examined, with particular emphasis
on published fluid pressure and formation depth as indicated by fluid inclusion data and geological reconstruction. Defining
an arbitrary subdivision at a molar Cu/Au ratio of 4.0 × 104, copper–gold deposits have a shallower average depth of formation (2.1 km) compared with the average depth of copper–molybdenum
deposits (3.7 km), based on assumed lithostatic fluid pressure from microthermometry. The correlation of Cu/Au ratio with
depth is primarily influenced by the variations of total Au grade. Despite local mineralogical controls within some ore deposits,
the overall Cu/Au ratio of the deposits does not show a significant correlation with the predominant type of Cu–Fe sulfide,
i.e., chalcopyrite or bornite. Primary magma source probably contributes to metal endowment on the province scale and in some
individual deposits, but does not explain the broad correlation of metal ratios with the pressure of ore formation. By comparison
with published experimental and fluid analytical data, the observed correlation of the Cu/Au ratio with fluid pressure can
be explained by dominant transport of Cu and Au in a buoyant S-rich vapor, coexisting with minor brine in two-phase magmatic
hydrothermal systems. At relatively shallow depth (approximately <3 km), the solubility of both metals decreases rapidly with
decreasing density of the ascending vapor plume, forcing both Cu and Au to be coprecipitated. In contrast, magmatic vapor
cooling at deeper levels (approximately >3 km) and greater confining pressure is likely to precipitate copper ± molybdenum
only, while sulfur-complexed gold remains dissolved in the relatively dense vapor. Upon cooling, this vapor may ultimately
contract to a low-salinity epithermal liquid, which can contribute to the formation of epithermal gold deposits several kilometers
above the Au-poor porphyry Cu–(Mo) deposit. These findings and interpretations imply that petrographic inspection of fluid
inclusion density may be used as an exploration indicator. Low-pressure brine + vapor systems are favorable for coprecipitation
of both metals, leading to Au-rich porphyry–copper–gold deposits. Epithermal gold deposits may be associated with such shallow
systems, but are likely to derive their ore-forming components from a deeper source, which may include a deeply hidden porphyry–copper
± molybdenum deposit. Exposed high-pressure brine + vapor systems, or stockwork veins containing a single type of intermediate-density
inclusions, are more likely to be prospective for porphyry–copper ± molybdenum deposits. 相似文献
3.
《吉林大学学报(地球科学版)》2015,(Z1)
<正>铜(Cu)和锌(Zn)属于第一过渡族金属元素,分别有2种(63Cu、65Cu)和5种(64Zn、66Zn、67Zn、68Zn、70Zn)稳定同位素。Cu-Zn都属于生命元素,它们在海洋中的地球化学循环对海洋生产率发挥着重要作用。现有研究表明,海水的δ65Cu和δ66Zn分别为ca.0.9‰和ca.0.5‰,显著重于河水的Cu-Zn同位素组成(δ65Cu=ca.0.6‰和δ66Zn=ca.0.3‰);说明海洋中至少存在一个具有轻Cu-Zn同位素组成的储库。海底Fe-Mn结壳和碳酸盐岩石海洋Cu-Zn输出的重要渠道。已有研究表明,三大洋中的Fe-Mn结壳的δ65Cu和δ66Zn分别为0.44±0.23‰和1.04 相似文献
4.
MC-ICP-MS高精度Cu、Zn同位素测试技术 总被引：4，自引：1，他引：3
过渡族元素同位素是国际上同位素地球化学研究的热点。测试技术的限制是制约过渡元素同位素研究发展的关键。笔者利用Neptune型多接收等离子质谱(MC-ICP-MS),采用Cu、Zn互为内标的方法对仪器的质量歧视进行了校正,对基质效应和测试方法的重现性进行了检验,建立了高精度的Cu、Zn同位素测试技术。在5个月内对实验室标准IMRCu和IMRZn进行了测量,结果分别为δ65CuNIST976=(0.34±0.08)‰(2SD,n=32),δ66ZnJMCZn=(-9.64±0.05)‰(2SD,n=26),δ67ZnJMCZn=(-14.37±0.16)‰(2SD,n=26),δ68ZnJMCZn=(-19.01±0.08)‰(2SD,n=26),分析精度达到国际同类实验室先进水平。对Cu、Zn同位素参考物质进行了对比测量,分析结果与报道值在误差范围内完全一致。 相似文献
5.
6.
我国首次发现的Cu6SnWS8矿 总被引：1，自引：0，他引：1
Ｃｕ６ＳｎＷＳ８矿是一种罕见矿物，在我国属首次发现，该矿物平均化学成分为：Ｃｕ４０．１９％，Ｓ ２６．２３％，Ｗ ２０．０２％，Ｓｎ １３．４９。本文就目前所获得的成果，介绍一下它的地质产状，伴生矿物及矿物的物理、化学特征。 相似文献
7.
在分析河南黄淮平原土壤和小麦籽实中Cu含量分布特征的基础上,利用单项污染指数法对研究区小麦籽实中Cu的污染状况进行评价。其结果为：研究区小麦籽实中Cu的单项污染指数Pi的平均值为0．473,说明研究区小麦籽实未受Cu的污染。Cu的状况良好。进一步讨论了土壤中Cu的含量与小麦籽实中Cu含量间的关系。认为小麦籽实中Cu的积累与土壤中的总Cu无明显的相关关系,而与土壤中的有效态Cu含量具有明显的相关性。据此,将土壤有效态Cu作为土壤Cu生态安全评价的指标。并建立了小麦籽实Cu与土壤有效Cu的响应关系模型,确定了土壤中有效Cu的安全界限值。 相似文献
8.
Please refer to the attachment(s) for more details. 相似文献
9.
10.
为分析湖北省鄂东南铜绿山地区Cu元素分布特征,采用能谱密度-面积多重分形模型(S-A方法)与传统地球化学数据处理方法,对1∶100 000水系沉积物地球化学数据进行分析,圈定了Cu元素地球化学异常区域。结果表明,圈定的异常区域能够为区域矿产预测提供支撑。 相似文献
11.
《吉林大学学报(地球科学版)》2015,(Z1)
<正>作为重要的过渡族金属元素和营养元素,Cu的地球化学循环对海洋生命演化非常重要[1]。而海洋中的Cu大多来自大陆风化输入,因此研究风化过程的Cu同位素分馏行为至关重要。岩石风化过程会释放金属离子进入水体,进而影响金属离子在水圈和岩石圈的地球化学循环过程,研究风化过程Cu同位素分馏情况能够更好地应用Cu同位素解释自然环境中Cu同位素变化及其循环过程。前人主要集中研究酸性条件下的含Cu硫化物淋洗过程中Cu同位素变化[2-5],但含Cu硫化物中的Cu只占硅酸岩总Cu中的 相似文献
12.
Hexagonal birnessite (δ-MnO2) is a close analogue to the dominant phase in hydrogenetic marine ferromanganese crusts and nodules. These deposits contain ∼0.25 wt.% Cu which is believed to be scavenged from the overlying water column where Cu concentrations are near 0.1 μg/L. Here, we measured the sorption of Cu on δ-MnO2 as a function of pH and surface loading. We characterized the nature of the Cu sorption complex at pH 4 and 8 using EXAFS spectroscopy and find that, at pH 4, Cu sorbs to birnessite by inner-sphere complexation on the {0 0 1} surface at sites above Mn vacancies to give a three to fourfold coordinated complex with 6 Mn neighbors at ∼3.4 Å. At pH 8, however, we find that some Cu has become structurally incorporated into the MnO2 layer by occupying the vacancy sites to give 6 Mn neighbors at ∼2.91 Å. Density functional calculations on and clusters predict a threefold coordinated surface complex and show that the change from surface complexation to structural incorporation is a response to protonation of oxygens surrounding the vacancy site. Consequently, we propose that the transformation between sorption via surface complex and vacancy site occupancy should be reversible. By fitting the Cu sorption as a function of surface loading and pH to the formation of the observed and predicted surface complex, we developed a surface complexation model (in the basic Stern approximation) for the sorption of Cu onto birnessite. Using this model, we demonstrate that the concentration of inorganic Cu in the deep ocean should be several orders of magnitude lower than the observed total dissolved Cu. We propose that the observed total dissolved Cu concentration in the oceans reflects solubilization of Cu by microbially generated ligands. 相似文献
13.
研究Cu2+污染物对桂林红黏土土性异变的影响。通过开展XRD、XRF及压汞试验,探讨Cu2+污染红黏土中主要矿物成分的异变规律及微观孔隙结构的变化趋势,结果表明:红黏土中主要矿物成分为高岭石、石英和针铁矿,Cu2+污染对这3种主要矿物成分的含量产生显著影响,随着Cu2+浓度的增大,高岭石和针铁矿的含量逐渐减少,石英的含量逐渐增多,其含量变化率大小关系为:高岭石>针铁矿>石英,且在浓度为2%时,高岭石的损失率高达10.69%,针铁矿的损失率达到5.38%;红黏土孔隙分布曲线为双峰分布,双峰分别分布在0.01-0.1 μm和1~10 μm之间,且在0.01~0.1 μm之间的微小孔隙占了绝对优势。随着Cu2+浓度的增加,"双峰"逐渐右移,孔隙变大;"峰宽"逐渐变宽,孔隙变多。通过开展相关力学试验,观察Cu2+污染红黏土的变形强度特性异变规律,试验结果表明:Cu2+污染对红黏土的变形强度特性影响显著。随着Cu2+浓度的增加,土体的无侧限抗压强度、抗剪强度、黏聚力C和内摩擦角φ逐渐减小,初始孔隙比e0和压缩系数α逐渐增大;当Cu2+浓度从0增大至2%时,土体应力-应变关系曲线由典型的应变软化型转变为弱应变硬化型,无侧限抗压峰值强度减少了76.91%,抗剪强度平均损失率达到69.36%。 相似文献
14.
采用纯水，氢氟酸处理样品，结合高灵敏的ＧＦＡＡＳ测定四氯化硅中超痕量Ｆｅ、Ｃｕ、Ｎｉ、Ｍｎ、Ｃｒ。方法简便、快速、灵敏度高、各元素的检出限（ｎｇ／ｍＬ）分别为Ｆｅ５，Ｎｉ０．８，Ｃｕ，Ｃｒ０．５，Ｍｎ０．２。 相似文献
15.
在贵阳市城区按七大城市功能分区采集灰尘样品,研究贵阳市不同功能区地表灰尘Cu水平及粒级效应。结果表明,贵阳市地表灰尘中Cu(≤105μm)含量数据符合对数正态分布,几何平均值为133 mg/kg。城市功能使贵阳市地表灰尘Cu累积呈现三种程度,累积最重的是工业区,累积最轻的是学校与商贸区,其中,工业区地表灰尘Cu含量显著高于商贸区和学校。贵阳市地表灰尘Cu主要富集于中等粒级(250～105μm),但工业区和住宅区的地表灰尘Cu主要富集于细粒级。所有功能区均显示粗粒级对灰尘Cu的贡献最小。 相似文献
16.
《矿物学报》2016,(1)
两江Cu矿床为一个位于广西中部的石英脉型矿床。为了查明矿床成因,笔者对该矿床分别进行了矿床地质和S-Pb同位素研究。结果表明,矿石硫化物S同位素的δ34SCDT介于-1.22~0.96‰之间,呈塔式分布,暗示矿石S为岩浆或深部热液起源。矿石Pb同位素的208Pb/204Pb、207Pb/204Pb和206Pb/204Pb的比值分别介于38.698~39.817、15.773~15.879和18.307~19.232之间,平均值分别为39.151、15.809和18.307。对比研究表明,矿石与地层(寒武系和泥盆系)砂页岩和加里东期岩浆岩完全不同的Pb同位素组成,而与晚白垩世岩浆岩(包括昆仑关黑云母花岗岩)具有较为相近分布范围。因此,该矿床的矿石Pb及其成矿金属物质最有可能起源于晚白垩世岩浆作用。结合矿体交截关系和成矿物质来源研究,笔者推测该矿床最有可能形成于晚白垩世。由于含矿石英斑岩为加里东期岩浆作用的产物,因此,在矿区深部存在与成矿作用有成生关系的隐伏岩体,很可能为昆仑关黑云母花岗岩岩基向西北方向延伸部分。区域矿化特征对比表明,大明山W-Cu多金属成矿带深部可能存在矽卡岩型矿化,并预示着巨大的找矿潜力。 相似文献
17.
我国部分地区土壤污染形势严峻,主要表现为Cu等重金属元素严重超标。污水灌溉以及含Cu饲料过量使用等不合理的农业生产方式是导致Cu在耕地中富集的主要因素,严重威胁粮食安全和人类健康。以河北保定典型污灌区为研究区,通过静态吸附批量实验探究土壤吸附Cu的动力学和热力学特性。吸附动力学模型和等温吸附经验模型中得到的参数一致表明,表层土壤S1对Cu的吸附能力强于底部土壤S2。S1的有机质含量高于S2,提供了更多的表面吸附点位,这可能是导致土壤S1对Cu的吸附能力更强的原因之一。离子强度对土壤Cu吸附率的影响较小。溶液pH和溶解性有机物(DOM)含量对土壤Cu吸附率的影响明显,pH值与吸附量呈正相关,DOM浓度与吸附量呈负相关。由于土壤对pH有很强的缓冲能力,短时间的酸雨可能不会导致Cu的迁移。施用有机肥时,有机肥浸出液中高浓度的DOM可能会与Cu形成水溶性Cu-DOM络合物,促进Cu在土壤中的迁移,导致浅层地下水污染。 相似文献
18.
《International Geology Review》2012,54(7):842-862
During late Palaeozoic time, extensive magmatism and associated ore deposits were developed in the eastern Tianshan orogenic belt (ETOB), Northwest China, which is part of the Central Asian Orogenic Belt. To understand the petrogenesis of the intrusions in this area, we performed in situ zircon U–Pb and Hf isotopic analyses on the Tuwu–Yandong (TW–YD) stocks and the Xianshan, Hulu, Luodong, and Poshi batholiths. Two major suites of intrusive rocks have been recognized in the ETOB: (1) 338–339 Ma plagiogranite porphyries and 265–300 Ma ultramafic and mafic rocks, of which the former are associated with 323 Ma porphyry Cu–Mo deposits and have enriched radiogenic Hf isotopic compositions (?Hf(t) = +11.5 to +15.6), which were derived from a depleted mantle source, whereas the latter are associated with 265–300 Ma magmatic Ni–Cu deposits and have variable Hf isotopic compositions (?Hf(t) = ?10.3 to +14.3), indicating an origin via the hybridization of depleted mantle magma and variable amounts of ancient lower-crustal components. The proposed magma sources, combined with the geochemical differences between these two suites of intrusive rocks, indicate that in the lower to middle Carboniferous, a N-dipping subduction zone beneath the Dananhu arc triggered the emplacement of granitic porphyries in the Tousuquan and Dananhu island arc belt in the east Tianshan, leading to the formation of the TW and YD porphyry Cu–Mo deposits. In the Upper Carboniferous to Lower Permian, large mafic–ultramafic complexes were emplaced during the closure of the ancient Tianshan Ocean, resulting in the formation of several magmatic Cu–Ni sulphide deposits. 相似文献
19.
Kalin Kouzmanov Robert Moritz Albrecht von Quadt Massimo Chiaradia Irena Peytcheva Denis Fontignie Claire Ramboz Kamen Bogdanov 《Mineralium Deposita》2009,44(6):611-646
Vlaykov Vruh–Elshitsa represents the best example of paired porphyry Cu and epithermal Cu–Au deposits within the Late Cretaceous
Apuseni–Banat–Timok–Srednogorie magmatic and metallogenic belt of Eastern Europe. The two deposits are part of the NW trending
Panagyurishte magmato-tectonic corridor of central Bulgaria. The deposits were formed along the SW flank of the Elshitsa volcano-intrusive
complex and are spatially associated with N110-120-trending hypabyssal and subvolcanic bodies of granodioritic composition.
At Elshitsa, more than ten lenticular to columnar massive ore bodies are discordant with respect to the host rock and are
structurally controlled. A particular feature of the mineralization is the overprinting of an early stage high-sulfidation
mineral assemblage (pyrite ± enargite ± covellite ± goldfieldite) by an intermediate-sulfidation paragenesis with a characteristic
Cu–Bi–Te–Pb–Zn signature forming the main economic parts of the ore bodies. The two stages of mineralization produced two
compositionally different types of ores—massive pyrite and copper–pyrite bodies. Vlaykov Vruh shares features with typical
porphyry Cu systems. Their common geological and structural setting, ore-forming processes, and paragenesis, as well as the
observed alteration and geochemical lateral and vertical zonation, allow us to interpret the Elshitsa and Vlaykov Vruh deposits
as the deep part of a high-sulfidation epithermal system and its spatially and genetically related porphyry Cu counterpart,
respectively. The magmatic–hydrothermal system at Vlaykov Vruh–Elshitsa produced much smaller deposits than similar complexes
in the northern part of the Panagyurishte district (Chelopech, Elatsite, Assarel). Magma chemistry and isotopic signature
are some of the main differences between the northern and southern parts of the district. Major and trace element geochemistry
of the Elshitsa magmatic complex are indicative for the medium- to high-K calc-alkaline character of the magmas. 87Sr/86Sr(i) ratios of igneous rocks in the range of 0.70464 to 0.70612 and 143Nd/144Nd(i) ratios in the range of 0.51241 to 0.51255 indicate mixed crustal–mantle components of the magmas dominated by mantellic signatures.
The epsilon Hf composition of magmatic zircons (+6.2 to +9.6) also suggests mixed mantellic–crustal sources of the magmas.
However, Pb isotopic signatures of whole rocks (206Pb/204Pb = 18.13–18.64, 207Pb/204Pb = 15.58–15.64, and 208Pb/204Pb = 37.69–38.56) along with common inheritance component detected in magmatic zircons also imply assimilation processes of
pre-Variscan and Variscan basement at various scales. U–Pb zircon and rutile dating allowed determination of the timing of
porphyry ore formation at Vlaykov Vruh (85.6 ± 0.9 Ma), which immediately followed the crystallization of the subvolcanic
dacitic bodies at Elshitsa (86.11 ± 0.23 Ma) and the Elshitsa granite (86.62 ± 0.02 Ma). Strontium isotope analyses of hydrothermal
sulfates and carbonates (87Sr/86Sr = 0.70581–0.70729) suggest large-scale interaction between mineralizing fluids and basement lithologies at Elshitsa–Vlaykov
Vruh. Lead isotope compositions of hydrothermal sulfides (206Pb/204Pb = 18.432–18.534, 207Pb/204Pb = 15.608–15.647, and 208Pb/204Pb = 37.497–38.630) allow attribution of ore-formation in the porphyry and epithermal deposits in the Southern Panagyurishte
district to a single metallogenic event with a common source of metals. 相似文献